Process for treating poor manganese ores containing phosphorus



- iron ore and 200 Patented Dec. 9, 1941 PROCESS FOR TREATING POORMANGA- NESE OBES CONTAINING PHOSPHORUS Hans Hahl, Volklingen,

by mesnc assignments, to Percy H. Royster,

Montclair, N. J.

No Drawing. Application May '1,

206,607. In Germany Saar, Germany, assignor,

1938, Serial No.

May 12, 1937 3 Claims. (Cl. 75-131) It is known that ferromanganese andother manganese alloys with a high percentage of manganese can only beores which are poor in phosphorus and besides manganese do not containmore than a certain quantity of iron. For the production offerromanganese, only high grade manganese ores can therefore be used.As, however, such ores are only to be found in a few districtsthroughout the world, it is important that it should be possible toproduce ferromanganese from manganese ores which are poor in iron andrich in phosphorus.

A way for solving this problem will be hereinafter described. Accordingto the invention the ores are first smelted in a blast furnace with acidslag yield. Thus a more or less strongly silicized crude iron isproduced which contains the whole phosphorus of the charge but onlylittle manganese. The greater portion of the sulphur-passes into theslag during the smelting owing to the high manganese content of thecharge. The ratio of distribution dependsupon the limeand manganesecontent of the slag. If the blasted crude iron contains too much sulphurthis is removed in known manner by desulphurizing agents, for instanceby solid or previously melted soda or by substances containing soda.

The acid slag produced during the smelting of the ore contains almostthe whole of the manganese contained in the charge but practically nophosphorus and thus constitutes a. raw material which is very suitablefor producing ferromanganese. The slag is again worked in a blastfurnace with an addition of sufiicient quantities of lime or limestone.At the same time by yield of a highly basic slag and by employingsufficient quantities of fuel and air of high temperature the greatestpart of the manganese is reduced. A highly basic slag poor in manganeseand a ferromanganese poor in For the reduction of the manganese anelectric furnace can also be used with advantage.

The following example illustrates th process: In the case of acidsmelting 1000 kilogrammes of Fernie-ore in dry state, that is a lowgrade German manganese ore containing in dry state 24% of iron, 19% ofmanganese and 20 to 25% phosphorus are formed. v

obtained from manganese v of silica, and commonly containing 20% ofhumidity, 1000 kilogrammes of Siegerland sparry kilogrammes of burntlime are charged. The coke addition amounts to 850 kilogrammes. Theresultant slag contains:

manganese, is reduced, and

. Per cent S102 30 Mn0=21% n 2'7 A1203 21 CaO 1'7 .FeO 2 The crud ironcontains:

Per cent h Si 2.5 Mn 0.4 C 3.0 P 0.7 S 0.0150.15 The acid slag is thensmelted in a, blast furnace with additionof the raw materials containingiron and poor in phosphorus, preferably such which themselves containmanganese. For the sake of simplicity it necessary quantity of is hereassumed, that calcined pyrites is added. The mixture for ferromanganesethen consists of Kgs. Slag from the preceding smelting with acid slagyield 1000 Burnt lime 300 Calcined pyrites -4 230 The slag producedduring the smelting with basic slag yield contains:

Per cent SiOz 26 CaO 43 A120: 11 Mn=round 8% MnO 6 The yield offerromanganese amounts to 280 kgs., the quantity of slag to 1400 kgs.,so that the proportion of metal to slag is 1:5. Nevertheless a yield inmanganese of 63% is attained. The total consumption of coke for carryingout the process is about 120% related to the yield of crude iron andferromanganese.

It has already been proposed, for the production of ferromanganese frompoor manganese ores to melt these ores with additions under a neutralor'weakly acid slag in a drum or rotary furnace, to treat the moltenslag at a low temperature with charcoal or some other reducing agent sothat the excess of iron, but notthe finally to smelt the slag rich inmanganese but poor in iron in the usual manner in a blast furnace.Thisprocess is unsuitable for the treatment of manganese ore containingphosphorus as the phosphoric acid will not be reduced during thetreatment of the molten slag in a drum or rotary furnace andconsequently will not combine with the reduced iron. Contrary to thisprocess carried out at low temperature, according to the invention thesimultaneous reduction of manganese is prevented in the first stage bythe addition oi. a strongly acid slag, a blast furnace being used and analmost complete reduction or the phosphorus which was present in thecrude ore being process according to the invenmore economical than theknown also applicable for impure manpig iron poor in manganese,

' 2. A process for treating poor manganese ore containing phosphorus,consisting in first smelting the ore in a blast furnace with acidburdening to a phosphorus pig iron poor in manganese and then chargingthe resultant slag rich in manganese and poor in phosphorus withaddition 01' a calcium base fiuxing agent into a blast furnace withbasic burdening to produce ferromanganese poor in phosphorus.

3. A process for treating poor manganese ore containing phosphorus,consisting in first smelting the ore in a blast iumace with acidburdening to a phosphorus pig iron poor in manganese, the charge in thefirst step being so proportioned that the ratio of 810: to C30 is notless than 1.75, and then charging the resultant slag rich in manganeseand poor in phosphorus with addition of a calcium base fiuiging agentinto a blast furnace with basic burdening to produce ferromanganese Doorin phosphorus.

HANS HAHL.

